Hi guys, another quick question, I just bought some blinds, and need to mount them, the "L" bracket like mount screws to the window frame, and the ceiling of the window. Do you see any problem with drilling and screwing into the vinyl window frame at the top? Far above where the actual window meets the frame?

I wouldn't recommend screwing anything into the vertical plane of your window assembly, the brackets are usualy meant to use one way or the other, not both. Use the pre-drilled holes in the long side ("ceiling side")of your L bracket and screw into the "ceiling" of your window opening box or the top side of your window opening, called the head jamb, with the backside, short side, window side of this L bracket far enough forward as recommended in the instructions to clear operation of your window and the clearance the instructions indicate. (Use the long side of the bracket up towards the header, lintel or beam above and screw only up towards the head jamb IOW screw up into the horizontal "roof" of the window opening).

The short side holes ("wall side" or in this case the side which will drop down in front of your window) of the L bracket is used to fasten to a wall or moulding when doing an outside mount, above and beyond the window opening. Your window covering should have come complete with instructions that explain this.

Often you need to substitute different screws for the soft cheap multi-purpose screws usually supplied. You may also need to pre-drill and use anchoring hardware if you are mounting into finished plaster work forward of the head jamb. Usually wood screws (sometimes longer than what is pre-packaged with window covering) work well when the head jamb is where you are mounting, be sure to drill the right size pilot hole for your screws (if you make it to wide the blinds may come down especially when you draw them up).

Thanks for the detailed reply. I'll check again about not using both sets of screws on the "l" brackets. I would be drilling into plaster, normally, I would use a butterfly metal anchor, but I don't think it's hollow above the window. So will a plastic "drywall" anchor have enough bite? I don't want to use self tapping, since I think that will crack the plaster.

It appears that there are places for 2 screws in each L bracket to screw into the roof. One hole, and a slot. It seems to me like that might be too much for such a small space, and could weaken the plaster and cause cracking..

Luckily it appears that there's metal lath behind the plaster around the windows, so it may not be too weak...

A contractor friend of mine told me that most windows should be framed in on top, so he said he wouldn't worry about an anchor, and just screw through the plaster into the wood. What do you guys think about this? Since it's a house that was built in 1941.. .

I took a stud finder and it did go off about 1/2" above the roof of the window...